/Engine/Source/Editor/UnrealEd/Public/Editor.h
Delegate type to handle viewing/editing a set of asset identifiers (which are packages or ids) in the reference viewer
typedef TMulticastDelegate_TwoParams< void, const [TArray](API\Runtime\Core\Containers\TArray)< [FAssetIdentifier](API\Runtime\CoreUObject\AssetRegistry\FAssetIdentifier) >, const [FReferenceViewerParams](API\Runtime\CoreUObject\AssetRegistry\FReferenceViewerParams) > FOnOpenReferenceViewer